Heterogeneity among AIDS retroviral genomes is a distinct feature of these Lentiviruses. Molecular cloning, restriction enzyme analysis, nucleotide sequencing, and polymerase chain reaction techniques were used to characterize isolates of Human Immunodeficiency Virus (HIV). The objective was to obtain information pertaining to the structure and diversity of HIV with respect to its pathogenicity and antigenic variability. In contrast to the numerous T cell lymphotropic HIV isolates we have cloned, experiments are in progress to obtain molecular clones from macrophagtropic isolates. It has been suggested that macrophages are the primary reservoir of HIV, sustaining a persistent infection in individuals for many year. A survivor T cell line (ACH-2) constituitively produces low levels of HIV particles. Compared to the infectious clone (pNL4-3) and pLAVbru, which produced viral particles after 7 days, ACH-2 viral supernatants produced two to four logs (TCID-50) less virus after 15 days. This cell line may provide information on the pathogenicity of HIV as it relates to persistence and/or latency and viral induction.